Ingenious Drywall Screw Cuts Noise Transmission in Half

One of the biggest complaints about the kind of multi-family housing that we promote on Treehugger is noise from neighbors that comes through the walls and ceilings. The problem can be even worse in wood construction, flanking around the edges of cross-laminated timber (CLT) panels or through wood stud walls in low-rise "missing middle" housing.

There are many approaches to dealing with the problem, but here is a new one: a special screw developed by Håkan Wernersson of Malmö University in Sweden. The "Revolutionary Sound Absorbing Screw" or "Sound Screw" is split in the middle with the two parts separated by a sort of spring which acts as a resilient mechanical coupling, which decouples the drywall from the stud. Wernersson says “with our screw, you can mount plasterboard directly to the walls, freeing up floor space, and a square meter of floor space can be worth thousands.”

The test data from a sound lab show that the Sound Screw reduces noise transmission by nine decibels. As the decibel scale is logarithmic, that is equivalent to cutting the noise level in half, a meaningful reduction.

There is a U.S. patent application by Wernersson that was granted in 2018, which Wennersson confirms is the right one: "The patent you refer to describes the principle that we still are using, with two screw parts connected with a spring and a bit that grabs both screw parts during mounting. But it looks quite different, as you can see in the picture."

The screw is described:

"A purpose of the invention is to be able to create conditions in a simple and cost efficient way for further improvements by reducing sound, vibration and/or heat conduction between the first and the second construction, for example between a frame work, as a first construction and a false ceiling or a wall, as a second construction. Another purpose of the invention is to further decrease the transmission of vibrations from the first to the second construction or vice versa in comparison to existing technique."

It appears the top half of the screw sockets into the bottom half under pressure while being installed, and then separates. However, it is designed to be as easy to use as a conventional drywall screw. The patent notes: "As mentioned above, a purpose of the invention is that the arrangement is formed so that the assembly shall be able to be performed in one moment similar to a regular screw and a screw driver. "

No word on what the screw will cost yet. According to Wennersson: “It has not entered the market yet, and we therefore need more examples of projects or installations where the screws are used.” It is being actively marketed through Akoustos, a company set up by Wennerson and acoustician Raimo Issal, who point out the benefits:

"It is easy to use. Replace your regular screw with a Sound Screw and your problems with unpleasant sound is solved, without adding extra building materials or extra work. It is tested with amazing results. When mounted the Sound Screw provides a resilient connection between panels and studs in a way where a substantial part of airborne as well as impact sound can be absorbed by the screws."

Is it better than the competition?

There are lots of other ways to deal with sound transmission through walls and ceilings, including resilient channels, long metal strips of folded metal that separate the drywall from the supporting studs; these are half an inch thick. As noted on our sister site The Spruce, one can also use soundproof drywall such as QuietRock, which is a sandwich of two thin layers of drywall with a filling of "viscoelastic sound-absorbing polymer." But these are expensive: According to The Spruce, a conventional sheet of drywall costs $7.50 and a sheet of QuietRock is $54.

Another method is to make your own sound-absorbing sandwich with "green glue" as the filling. The glue is expensive, but according to bettersoundproofing.com, it will be slightly cheaper than Quietrock.

All of these techniques require extra hardware or different (and expensive) materials. If the Sound Screw doesn't cost too much and is a straight substitution of one drywall screw for another that gives pretty much the same sound reduction as really expensive sound-absorbing drywall, then it might well be appropriately named a "Revolutionary Sound Absorbing Screw"

And if you are in a rental apartment and can't change the drywall, you can always go with books and tapestries.